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Larsen’s rift

Larsen A and Larsen B ice shelves are long gone, breaking from the Antarctic Peninsula in 1995 and 2002 respectively. Now researchers at Swansea University suggest that Larsen C, big brother to the two vanished shelves, is cracking up

Ice shelves are permanent extensions to an ice sheet, usually several hundred metres thick, that float on the Antarctic’s ocean fringes.

Satellite data from NASA was used to track rapid changes to a large rift that developed in Larsen C during 2014.

When the next ice calves – ice chunks that fall from a glacier or ice sheet – break away from Larsen C the shelf will be reduced by ten per cent, according to the research.

This is a massive chunk. The Larsen C shelf has an area two and a half times that of Wales and is the fourth largest ice shelf in the world.

‘It is not possible to predict when the ice will calve away, but when it does, it will be the largest event of its kind since the 1980s. A similar calving preceded the collapse of the Larsen B Ice Shelf in 2002,’ says Adrian Luckman, lead researcher on the project.

An Antarctic ice shelf (Image: Armin Rose)

Computer models show that once this latest collapse has happened the shelf will be left unstable, and at risk of further collapse.

‘Rifting and calving of this magnitude is not unusual. The critical thing is that our model shows that even for the most modest of projected calving extents, the remaining ice will be significantly less stable than at present,’ says Daniela Jansen, a researcher on the project.

There will be no immediate impact from the ice shelf collapse because the ice is already floating, but if Larsen C continues to collapse ice covering mountains in the Antarctic Peninsula pinned by the shelf may be released, contributing to sea level rise.

Although the latest collapse cannot be directly attributed to climate change, and may be part of a natural cycle, the Antarctic Peninsula is one of the fastest warming places on Earth.